Posted
by
Zonkon Saturday September 10, 2005 @07:32PM
from the i-had-dibs dept.

SocietyoftheFist writes "From an article on the BBC website, scientists have determined that Titan occupies a 'sweet spot' much like Earth. Venus is the same size as Earth but too hot so water boiled off long ago ending most geologic processes. Mars is too small to generate enough heat to keep water from freezing so it too slowed down geologically. Titan is much like the Earth with winds, rains and tectonic forces but instead of water it has an abundance of methane. Methane is liquid at the temperatures found in Titan's atmosphere and replaces water in the equation."

"Actually gasoline is typically octane.. not methane."True, the major components of gasoline are Octane and he[iane. Of course thare are many other additives including ethano;.

"Methane is very flammable.. you'd have to keep the gas compressed all the time.."

You'd have to keep it compressed because it is a gas at room temperature, so it would take up a lot of space. Of course you could keep it in a gas bag on the roof of the vehicle like people did in WWII with coal gas.

Hey, don't laugh it off so quickly. Conspiracy theorists might want to consult Stephen Baxter's Titan [amazon.com], in which the accidental destruction of the spaceshuttle Columbia on re-entry prompts a daring mission to Titan, to prep it for human colonization / mining (and it doesn't hurt that it comes at a time when NASA's funding is being reconsidered, and the program itself re-evaluated -- yup, still talking about the book).

Well, you have noticed the similarity between the "Men in Black" and restaurant waiters, haven't you? And you've noticed they delight in serving steaks? Well, that's what happens when the Titan aliens they've interrogated in Area 51 are finished with.

In both of their "sweet spot" scenarios, they attribute boiling water to solar proximity, but then frozen water to planetary mass. In both cases, the whole thing can be explained just with solar proximity, as it usually has been. Planets farther away have colder temperatures. Yes, its true that a smaller planet will retain less heat, but the primary factor here is still solar proximity.

We don't just retain heat, we generate heat. Otherwise the earth's core would have solidified a long time ago, and we'd be very irradiated.

Can you explain how the heat is generated? I always assumed that the Earth's core (and mantle) are hot because it takes a really long time for all that molten rock to cool off. All the rocks that collided together 4.5 billion years ago to form the Earth generated (past tense) a lot of heat from collisions, but there's no internal heat generator.

I believe you are mostly correct. There is obviously a substantial amount of heat generated by fission, but it isn't why the Earth is still hot. Also, I don't know if anyone has ever linked the latent heat of Earth to pulling us out of an ice age which is a purely atmospheric phenomenon. It is more closely linked to water and CO2 cycling I believe.

First, there's friction between the layers of gooey nougat inside the earth as they move at different velocities with respect to each other. Secondly, friction from the tectonic plates moving on top of that gooey nougat (the continents, by providing thicker insulation in parts, also assure temperature differentials in the gooey nougat, causing yet more motion). Third, tidal forces from the moon and the sun that stir the gooey nougat up as they move around (bringin

Lord Kelvin estimated the age of the Earth at about 20-40 million years, based on the science (thermodynamics) of his day, and how long it should have taken for the Earth to cool to its current state. He didn't, and couldn't have, taken into account decay heat from radioactive elements.

The boiling point of a liquid is determined both by its temperature and the atmospheric pressure. Mars has a thinner atmosphere because it can't hold as much gas. Oxygen on Mars is too light and escapes off the face of the planet, just as Helium and free Hydrogen do on Earth.

A fundamental issue, as I understamd it, is the speed of chemical reactions. Roughly speaking, chemical process speeds are related exponentially to temperature. Generally speaking, the temperatures on Titan are far to low to permit life processes anything like the sort we see on Earth. That isn't a definite "no", but any life forms would have to be radically different from anything on Earth.

Most likely, if there's any life it's by heat vents. They said Titan is geologically active, and appears to be erupting continuously. In that case, it's similar to life that exists in vents in the crust under the ocean. Those things do look other worldly, but I'd wager that its conceivable that a single-cell organism could develop by these geological hotspots.

Chemical reactions for life go too slowly at our temperature, too, and thank goodness they do or we would all chemically react ourselves into a pile of goo in a matter of a few minutes.

You want reactions that are slow, but that can be sped up using a catalyst when necessary. That allows you to control the reactions and switch them on and off as needed. In biological systems enzymes are the catalysts.

Yes. What that means is that reactions that are "just right" on earth will be too slow on Titan. But there are almost certainly equivalent reactions that would be too fast at our temperatures but just right on Titan. They wouldn't even have to be radically different.

While the methane jokes are just HI-larious, on a more serious/sci-nerd note:

Methane is a lot less likely to be the "solvent" for life as water is. Water has a lot of very unusual properties which are important factors in the biochemical reactions of life; the most important of these is its strong polar nature. The polarity of water is a, if not the (biochemists feel free to correct me, i'm synthetic org.), major factor in protein folding; the ability of water to dissolve ionic compounds is also vitally important, e.g. nerve function. Bottom line, a nonpolar organic solvent is a *lot* less likely, if not impossible, to support life.

It isn't just polarity; hydrogen bonding plays a huge part in creating the entropic effects necessary for protein folding, as well as the optimal heat capacity for maintaining a stable earth temperature.

But it still remains very interesting to study. All these problems you propose are valid, but the chemistry at those places could still be very complex, and the thing with life is, once it has started its' complexity will rise with the next generations.

Our experience life is, let's face it, laughable. We only have one genesis to work with. The premise of liquid water is solely based on Earth observations. I don't know about you, but at least I don't know about any holiday resort on Earth next to a liquid methane lake. there just aren't any.

If I hear about an energy source, complex carbon-based chemicals and a liquid to mix them, then, with an open mind, I think some emerging intelligence may occur after billions of years. Even if it is a freak accident, if you believe a complex system can exist for even a few hundred millions of years without one freak accident, then you're obviously not an engineer. Maybe it will not be life as we know it, but damnit Jim, it will be alive!

Even if it is a freak accident, if you believe a complex system can exist for even a few hundred millions of years without one freak accident, then you're obviously not an engineer

Except it doesn't require just any freak accident, it would require one very specific type of freak accident to generate life. In fact, since we still don't know exactly how life is generated we really can't say what is required for it to come about.

there is one train of thought that life is actually a cosmic imperitive so to speak. in that if it's even remotely possible, then life will occur. the reasoning behind this is that we can find life in boiling springs, frozen rocks and many km's under the sea in total darkness. if life can survive in such conditions, then maybe it's not some rare fragile occurance, but a force in the universe which is just begging to happen anywhere possible.

here is one train of thought that life is actually a cosmic imperitive so to speak.

But that's metaphysics, not science.There is a story of a puddle which forms in a hole in some cement. The puddle thinks "ooooo what a nice hole, it fits me perfectly, it must have been made for me. The puddle keeps thinking this right up until the last drop dries up.

My personal opinion is that "life" is just a word with no particular meaning. Some systems appear to be "alive" to us because we are systems evolved to distingui

Since we haven't found something we want to calllife anywhere other than Earth yet, we are looking at a 0% chance based on past results.

From a purely statistical perspective, this is incorrect. The sample size is not large enough for any conclusions to be drawn about the frequency of life throughout the universe, or even just the galaxy.

The polarity of water is a, if not the (biochemists feel free to correct me, i'm synthetic org.), major factor in protein folding;

Proteins fold no matter what environment they are in, they simply fold differently in different environments. There is no reason to believe that folding in solvents other than water would be any worse for evolving life than folding in water.

the ability of water to dissolve ionic compounds is also vitally important, e.g. nerve function

Low. From what I understand, most of the star systems we've been able to watch closely have superjovian planets in orbit around them, and they don't bode well for life. Jupiter itself is yet another "sweet spot," big enough to sweep the solar system of most of the extinction-causing comets/asteroids/etc, but not so big as to suck us up. Planets that are 10's or 100's of jovian masses don't allow for many other planets (let alone rocky planets with a fluid iron core at the correct distance from the system

From what I understand, most of the star systems we've been able to watch closely have superjovian planets in orbit around them

That was a long time ago, and it was only because the doppler-shift techniques used for detecting them were intially only sensitive enough to detect massive super-jovian planets.

If you take a look at an extra-solar planets catalog [obspm.fr] you'll find lots of sub jovian planets. Note that a lot of them have pretty short periods, but again this is more a feature of the way they're detected, a

So it's 0.00004% of one civilization, and not "millions" as you cite. You need to gather 2,500,000 of "our galaxies" to get to one civilization, and you already have one, so go and get another 2.5 million of galaxies if you need aliens.

Methane clathrate deposits in the ocean floor have been found to be inhabited by polychaete worms of the species Hesiocaeca methanicola. The worms colonize the ice-methane solid and appear to survive by gleaning bacteria that in turn metabolize the clathrate.
In 1997, Charles Fisher, professor of biology at Penn State, discovered this remarkable creature living on mounds of methane ice under half a mile of ocean on the floor of the Gulf of Mexico.

Sometimes I've wondered what would happen if we could (magically) replace our moon with Titan. It's larger than the moon so tidal effects and animal life here on earth will be affected of course, but what would happen to Titan's atmosphere? Huge greenhouse effect?
Europa would be an interesting candidate too... but maybe this sort of speculation belongs in the 'Who would win: Skeletor vs Dr.Doom' category.

Possibly. But not for very long, at least in the geological sense. Titan's able to maintain its dense atmosphere because it is so bitterly cold. The kinetic energy of its atmospheric gas molecules is not very high, so Titan's weak gravity is able to hold onto them. With significant heating, the atmosphere would bleed away.

Quite a lot of Titan is made out of ices. These will replenish the escaping atmosphere, for a while. But it also means

How is this meant with the boiled water? That it boiled because of the greenhouse effect? I read several times that Venus would be habitable (although surely not very pleasant, and mostly a desert world) if the greenhouse gases weren't there, and a earth-like atmosphere would be in their place.

unless you've got an adimantium spine and legs I don't think humans will be living on Venus. The gravity alone is enough to crush a man like a empty soda can. The environmental pressure doesn't help either... from my understanding.

The article is making a pretty long assumption in equating 'habitable' with 'geologically active surface'.

Surface life may well prove to the the rarity.

Somewhere like Ganymede, or Europa, has a far greater habitability beneath the surface.

Sub-surface regions seems generally more likely to allow life to get started than surfaces. A bit of activity there is good, as life thrives in changing rather than fixed environments (as far as we know).

Surprisingly, I think there is quite a lot. Most of the minerals that make up Earth's crust contain water, and water, under pressure is drawn down into the crust at spreading faults. Also the carbonate minerals would not exist without long-lasting oceans where CO2 and silicate rocks can slowly combine. These hydrated and carbonate minerals act, I think as a lubricant to plate movements. I am not a geologist, but I'm sure I read this somewhere once. I can't quickly find confirmation.

It's correct that fault moovement and plate tectonics does not require water or other fluids, but in the majority of cases large shear-zones and falut systems show that water or other fluids (CO2, SO2) may have contributed to the ease of moovement. For instance in many thrust fault systems the sole throust is often located in shales which is rich in hyrdous minerals such as biotite, muscovite, chlorite or clay minerals. These minerals often act as the geological equvivalent of grease.In the case of thrust

Oh it doesn't? Do you have a counter-example of life for us to look at that isn't carbon based, and mostly water and oxygen breathing? (well, trees breathe CO2 for the carbon content, but trees need oxidants too).

If so, please contact someone in the scientific community immediately.

Do you have an example to prove that life must be carbon based, and mostly water and oxygen breathing? Let's face it, our little planet is unique right now. It could swing either way. One example - us - is hardly sufficient to prove a model. There are physical properties about the elements and molecules that make life possible on this planet, but only our life. Truth be told we don't quite know how life ever came into existence. Until we find another form of life that didn't come from our little back-water

Yep, The evolution of the 'cyano bacteria' (which can 'run' in both reducing and oxidizing environments, that with and without free oxygen) caused the biggest and most far reaching ecologic sdsiaster this planet has ever witnesed. Now only some deap sea hot springs (black smokers etc) and other special areas on earth exsists where the bacteria who evolved before said cyanos can still thrive (and those places can be the place for some realy bizare life forms.Yours Yazeran

not all life has to be carbon-based, mostly water, and oxygen-breathing.

That is true, but you also have to take into account the fact that solid water (ice) is less dense then liquid water. We take it for granted, but think about how it affects our planet. The bottom of the ocean is not solid like the bottom of a methane ocean. They are liquid and at a controlled temperature (4 degrees celcius). How much of a role does this little oddity of water play into our planet's evolution?

You don't choose your equations, you have to stick with what actually happens. You put a match the methane it reacts with oxygen to produce CO2 and water, that's what happens, you don't get to choose. You're right, that won't work in space, that's why methane won't burn in space, which was my point - Titan, taken as a whole, is in space.

Cue umpteen posts noting that there's no oxygen for the methane to combust with. Follow with posts noting the redundancy and anal nature of the preceeding posts. Follows those with posts arguing the relatively humorous nature of the posts preceeding the preceeding posts. Mix thoroughly, bake at brainstorm temperature, serves as many/.ers as bother reading.

And to extract it from the water ice you need fire to melt the ice and electricity to seperate the oxygen.It takes 118 kcal to turn two H20 molecules into one 02 molecule (I'm ignoring the hydrogen as waste for the moment.)

You need two O2 molecules to react with one molecule of methane. This reaction will produce191.6826 kcal.

Which means that it would take a net energy input of 44 kilocalories per each molecule of methane that you burn.

You better make that a large fire to start with because it will only get

Take a look at calcium for example. Have you ever noticed how coral skeletons share ALOT in common with limestone formations in a cave? It's just the structure calcium follows, perhaps the corals just take advantage of this fact and nurture it's natural crystalline form to create their skeletons. Some formations in caves are so spot on that they refer to the formation as 'cave coral'.

"The earth also had a hot core but that isn't near enough to keep it heated. "

It's hot enough to keep certain organisms that rely on chemosynthesis [wikipedia.org] alive at the ocean bottom, where no radiation from the sun reaches. There's little reason to believe this process couldn't happen on any reasonably volcanic body.

Folks, Vonnegut is "Kurt Vonnegut, Jr.", the referenced work is "The Sirens of Titan", and the "ice-nine" reference is from another book: "Cat's Cradle".

In "The Sirens of Titan" (been years since I read it, so I'll try my best), one of Vonnegut's earliest works, much is made of the notion that Titan enjoyed conditions similar to Earth's as the article states, and so some of the action takes place on Titan, whi